Methodological research: open questions, the need for 'research on research' and its implications for evidence-based health care and reducing research waste.

With the ever increasing pace of research reports published, a new type of study has emerged, in which researchers analyze research practices and provide methodological guidance for the future. The overall aims of such studies are to explore planning, conduct, reporting, dissemination, and evaluation of research, and to provide recommendations for their improvement. A myriad of studies have shown that studies are planned, conducted and reported in a suboptimal way, and that there is ample room for improvement. It has been suggested that studies with inadequate planning, conduct and reporting represent avoidable research waste, causing enormous waste of funds and researchers’ efforts, and yielding suboptimal research reports. Methodological studies represent research efforts that may help in reducing research waste, and therefore should be welcomed as a valuable contribution that may contribute to production of better evidence and justify investments in research. However, there are multiple open questions about what exactly is analyzed in such studies, which collective name we should use for them, what type of study designs can be considered methodological studies, are they synonymous with systematic reviews and metaanalyses (SR/MA), and so on. Methodological studies may be observational or interventional. The unit of analysis in observational methodological studies can be broadly described as a research-related report. Such reports can be very diverse, including, but not limited to, study protocols, datasets, full reports with data analyses, and summary formats such as abstracts, plain language summaries, and so on. These reports may or may not be published in peerreviewed literature. Some of those research-related reports that are not published in peer-reviewed literature are available online, including materials posted in registries and repositories, or organizational web sites. Interventional methodological studies explore various interventions for improving research.